feat: 重构前后端架构，添加Go后端和Python Agent服务

- 新增 Go 语言后端服务(server/)，包含用户认证、Agent管理、数据库连接等API
- 新增 Python Agent 服务(agent/)，实现Agent核心逻辑和工具集
- 前端从原生HTML迁移到Vue.js框架(web/src/)
- 添加 Docker Compose 支持(docker-compose.yml)
- 添加项目架构文档(docs/ARCHITECTURE.md)
- 添加环境变量示例(.env.example)和本地启动脚本(start-local.ps1)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/internal/handler/auth_handler.go

@@ -0,0 +1,80 @@
+package handler
+
+import (
+	"net/http"
+
+	"x-agents/server/internal/service"
+
+	"github.com/gin-gonic/gin"
+)
+
+type AuthHandler struct {
+	authService *service.AuthService
+}
+
+func NewAuthHandler(authService *service.AuthService) *AuthHandler {
+	return &AuthHandler{authService: authService}
+}
+
+type LoginRequest struct {
+	Username string `json:"username" binding:"required"`
+	Password string `json:"password" binding:"required"`
+}
+
+type LoginResponse struct {
+	Token string      `json:"token"`
+	User  interface{} `json:"user"`
+}
+
+// Login 处理登录
+func (h *AuthHandler) Login(c *gin.Context) {
+	var req LoginRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	resp, err := h.authService.Login(service.LoginRequest{
+		Username: req.Username,
+		Password: req.Password,
+	})
+	if err != nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, LoginResponse{
+		Token: resp.Token,
+		User: gin.H{
+			"id":       resp.User.ID,
+			"username": resp.User.Username,
+			"email":    resp.User.Email,
+			"role":     resp.User.RoleID,
+		},
+	})
+}
+
+// Register 处理注册
+func (h *AuthHandler) Register(c *gin.Context) {
+	var req struct {
+		Username string `json:"username" binding:"required"`
+		Password string `json:"password" binding:"required"`
+		Email    string `json:"email"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	user, err := h.authService.Register(req.Username, req.Password, req.Email)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusCreated, gin.H{
+		"id":       user.ID,
+		"username": user.Username,
+		"email":    user.Email,
+	})
+}